From time to time, fasteners, such as bolts, pins, rivets or the like, may need to be removed from various structures in order to partially or completely disassemble the structures. For example, various structures, including aircraft, undergo life cycle testing that requires at least some disassembly at one or more intervals during the lifetime of the structure. Additionally, structures that are involved in accidents may be disassembled during the investigation into the cause and/or the results of the accident.
In instances in which fasteners are removed from a structure, the fasteners are preferably removed without damaging either the fastener or the workpiece. In this regard, the structure from which fasteners are removed is frequently reassembled following an inspection and/or the performance of various maintenance activities. As such, it would be desirable, both from a cost and an efficiency standpoint, to reassemble the structure utilizing most, if not all, of the same components. By removing the fasteners without damaging the fasteners or the workpiece, the same fasteners can subsequently be reinstalled without having to rework the workpiece and, in particular, without having to rework the apertures defined by the workpiece in which the fasteners are installed. Moreover, in instances in which fasteners are removed from a structure in order to perform life cycle testing or during an accident investigation, the evidentiary value of the fasteners, as well as the workpiece, is significantly diminished if the condition of the fastener and/or the workpiece is altered or damaged during the disassembly process.
Conventional techniques for removing a fastener utilize a drift or a punch to apply axial force to the end of the fastener opposite the head end so as to push the fastener out of the corresponding aperture defined by the workpiece. With respect to a bolt, for example, the nut must first be removed from the threaded end of the bolt and a drift or punch is then utilized to push the bolt out of the corresponding aperture. Depending upon the design of the structure, however, the end of the fastener opposite the head end, such as the threaded end of a bolt, may be relatively inaccessible such that a drift or a punch cannot be utilized to push the fastener out of the corresponding aperture. In these situations, a wrench or the like may oftentimes be inserted from a direction substantially perpendicular to the longitudinal axis of the bolt so as to engage and remove the nut from the fastener. However, the surrounding structure oftentimes prevents access to the threaded end of the bolt with a drift or punch to thereafter remove the bolt.
Additionally, some structures may be at least partially forward of relatively soft material, such as aluminum, that may be damaged by the use of a drift or punch, thereby further limiting the use of a drift or punch. Furthermore, some structures may define at least partially threaded apertures that threadably engage the fastener, such as a bolt or the like. In these instances, a drift or punch is also generally inappropriate since attempts to merely push the fastener out of the threaded aperture would be either ineffective and/or would damage the threads defined by the aperture and/or the fastener.
In these instances, a fastener must generally be pulled or pried out of the corresponding aperture from the head end of the fastener. In order to pull a fastener out from the head end, a vice grip, pliers or the like are utilized to grasp the head end of the fastener. However, the force required to pull a fastener, such as a bolt, from the corresponding aperture may be substantial due, at least in part, to the generally snug fit of the fastener within the aperture. Moreover, it is generally difficult to securely grasp the head end of the fastener and the vice grip, pliers or the like may tend to slip off if attempts are made to pull the fastener.
Depending upon the structure from which the fasteners are extracted, the head end of the fastener may be inaccessible with a vice grip, pliers or the like. In addition, pulling a fastener from the corresponding aperture may damage the head end and/or threads of the fastener as well as the aperture. For example, the pulling force applied to the fastener may serve to misalign the fastener relative to the aperture, thereby damaging the fastener and/or the aperture. As a result of the relatively tight tolerances between the apertures defined by the workpiece and the corresponding fasteners, pulling the fasteners from the corresponding apertures may also induce thread scrubbing of the fastener and, in instances in which the aperture is threaded, of the threaded aperture.
In these instances in which the fastener is damaged during its removal, the fastener must generally be replaced prior to reassembly of the structure. Additionally, any apertures that were damaged during the disassembly process must be reworked prior to reassembly of the structure, thereby significantly increasing the time and expense associated with reassembling the structure.
As such, it would be desirable to provide an improved tool for removing fasteners from structures without damaging the fasteners or the structure, thereby permitting the structure to be reassembled utilizing the same fasteners with a minimum, if any, rework of the structure. In addition, it would be desirable to provide an improved tool for removing fasteners from workpieces in instances in which the end of the fastener opposite the head end is inaccessible with a drift or a punch.